Modern industrial processes create a wide range of unuseable waste products. In addition, large amounts of refuse of various kinds from domestic households and institutions are generated. All of these waste materials require non-polluting disposal or destruction. A number of disposal techniques are known but these techniques mainly have application to specific types of waste. Municipal refuse, for example, may be comminuted, separated into useful and waste components and the waste components destroyed by combustion, the ash residue being disposed of as landfill. Acid wastes from industrial processes may be neutralized with caustic and the neutral product disposed of in waterways. Alkaline wastes may be similarly neutralized and discharged into waterways. Toxic wastes and other hazardous sludges may be encapsulated into a structural material, for example, a fly ash/hydrated lime mixture and the resultant product disposed of in landfill. The problem faced by industry and by municipalities has been to devise waste treatment or waste disposal methods which produce non-polluting, small volume effluents, making use of facilities which are economic to construct and operate and which are capable of treating more than one type of waste product.